Ethyl Ascorbic Acid

If vitamin C had a clever little cousin who was less fussy, more stable, and still wanted to do all the skincare work, Ethyl Ascorbic Acid would be it. Pure ascorbic acid is brilliant on paper, but it is also notoriously temperamental: it oxidizes easily, turns brown, and loses potency. By adding an ethyl group, chemists made a derivative that is much more stable and can be used in formulas that play nicely with both water and oil. That stability matters because your serum can only help your skin if the vitamin C is still alive and kicking when you apply it.

The big question with any vitamin C derivative is whether it can actually get into your skin and do anything useful there. The answer here looks promising. A 2017 ex vivo skin penetration study found that Ethyl Ascorbic Acid could penetrate the skin and, in that setup, appeared to get in better than ascorbyl glucoside. There’s also the chemistry angle: it contains a relatively high amount of vitamin C equivalent material, around 86.4%, which is one reason formulators like it so much. Once inside the skin, it is thought to be converted into ascorbic acid, though that part is still mostly supported by manufacturer data rather than a long parade of independent human trials.

As for what you can expect on your face, this ingredient is mainly prized for the classic vitamin C perks: antioxidant protection, support for collagen, and helping to brighten dull or uneven-looking skin. The brightening part is where it has the most concrete evidence. In a small 8-week in vivo study, a 2% formula improved skin tone and lightened skin appearance in real people, which is pretty encouraging if your main goal is a more luminous complexion. The evidence for collagen boosting and anti-inflammatory effects is more suggestive than definitive, but overall Ethyl Ascorbic Acid looks like a smart, stable option if you want vitamin C benefits without the drama of a highly unstable formula.

A very stable and promising form of the skincare superstar, Vitamin C. If you do not know why Vitamin C is such a big deal in skin care, you can catch up here. In short, Vitamin C has three proven magic abilities: antioxidant, collagen booster, and skin brightener. The problem, though, is that it's very unstable, turns brown and becomes ineffective in no time (after a few month) and the cosmetics industry is trying to come up with smart derivatives that are stable and have the magic properties of pure Vitamin C. 

Ethyl Ascorbic Acid or EAC for short is an "etherified derivative of ascorbic acid" that consists of vitamin C and an ethyl group bound to the third carbon position. This makes Vitamin C very stable and soluble in both water and oil.

However, for a Vitamin C derivative to work it's not enough just to be stable, they also have to be absorbed into the skin and be converted there to pure Vitamin C. We have good news regarding the absorption: on top of manufacturer claims, there is some data (animal study) demonstrating in can get into the skin, and it seems to be better at it than Ascorbyl Glucoside, another vitamin C derivative.

Regarding conversion, we can cite only a manufacturers claim saying that EAC is metabolized in the skin into pure ascorbic acid (and the ascorbic acid content of EAC is very high - 86,4% - compared to the usual 50-60% Vitamin C content of other derivatives). 

As for the three magic abilities of Vitamin C, we again mostly have only the manufacturer's claims, but at least those are very promising. EAC seems to have both an antioxidant and anti-inflammatory effect, and it's claimed to be able to boost the skin's collagen production. The strong point of EAC though is skin brightening. On top of manufacturer claims, there is also clinical in-vivo (tested on real people) data showing that 2% EAC can improve skin tone and whiten the skin. 

Overall, Ethyl Ascorbic Acid is a very promising but not a fully proven Vitamin C derivative. It's worth a try, especially if you are after Vitamin C's skin-brightening effects.